Nomenclature of pyroxenes.

Morimoto, Nobuo

doi:10.2465/minerj.14.198

Cited by 546 publications

(685 citation statements)

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“…The clinopyroxene phenocrysts (Table 2) of the host basalt are both diopside and augite (after the nomenclature of [12]; Figure 3 …”

Section: Clinopyroxenementioning

confidence: 99%

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications

Mbowou¹,

Nguihdama²,

Yamgouot³

et al. 2017

OJG

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Wehrlite samples (size: ~4 cm) hosted in basaltic lavas from the SW of Hosséré Dammougalré are located in the western Adamawa Plateau. Porphyritic and allotriomorphic texture characterize respectively host Basalt and wehrlite xenoliths. The phenocrysts of olivine (Fo 68−74 ), and Ti-magnetite are scattered in host basalt. Wehrlite xenoliths (~4 cm size) contain Cr-rich clinopyroxene (diopise-augite), olivine (Fo 76−88 ) and chromiferous spinel. Equilibrium temperatures calculated from Fe/Mg exchange reaction for olivine/spinel vary between 944˚C and 1102˚C. The wehrlite olivine crystals with low Fo (<90) indicate a re-equilibration of Fe-Mg in the host basalt at low temperatures. All the analyzed wehrlite clinopyroxenes have crystallized at high pressures as evidenced by the Al vi and Al iv contents. The studied spinelbearing wehrlite xenoliths represent probably the residual portions of the upper mantle, which are an important source of information about lithospheric composition and thermal evolution beneath the Adamawa Plateau.

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“…The clinopyroxene phenocrysts (Table 2) of the host basalt are both diopside and augite (after the nomenclature of [12]; Figure 3 …”

Section: Clinopyroxenementioning

confidence: 99%

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications

Mbowou¹,

Nguihdama²,

Yamgouot³

et al. 2017

OJG

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“…The Morimoto (1989) classification of pyroxenes is used. Spinel compositions were recalculated on the basis of three cations, with Fe 3+ and Fe 2+ calculated by charge balance (Deer et al 1993).…”

Section: Methodsmentioning

confidence: 99%

Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

et al. 2015

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The ca. 30 Ma Steinberg basanite occurs at the NE termination of the Eger (Ohře) Rift in the NW Bohemian Massif, Central Europe, and belongs to the Cenozoic alkaline Central European Volcanic Province. The basanite hosts a suite of mantle xenoliths, most of which are harzburgites containing relatively magnesian olivine (Fo 90.5-91.6) and Alpoor (0.04-0.13 a pfu) orthopyroxene (mg# 0.90-0.92). Some of these harzburgites also contain volumetrically minor clinopyroxene (mg# 0.92-0.95, Al 0.03-0.13 a pfu) and have U-shaped LREE-enriched REE patterns. The Steinberg harzburgites are typical for the Lower Silesian -Upper Lusatian domain of the European subcontinental lithospheric mantle. They represent residual mantle that has undergone extensive partial melting and was subsequently affected by mantle metasomatism by mixed carbonatite-silicate melts. The Steinberg xenolith suite comprises also dunitic xenoliths affected by metasomatism by melt similar to the host basanite, which lowered the Fo content in olivine to 87.6 %. This metasomatism happened shortly before xenolith entrainment in the erupting lava. One of the xenoliths is a wehrlite (olivine Fo 73 %, clinopyroxene mg# 0.83-0.85, subordinate orthopyroxene mg# 0.76-0.77). Its clinopyroxene REE pattern is flat and slightly LREE-depleted. This wehrlite is considered to be a tholeiitic cumulate. One of the studied harzburgites contains clinopyroxene with similar trace element contents to those in wehrlite. This type of clinopyroxene records percolation of tholeiitic melt through harzburgite. The tholeiitic melt might be similar to Cenozoic continental tholeiites occurring in the Central European Volcanic Province (e.g., Vogelsberg, Germany).

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“…Wollastonite (CaSiO 3 ), a pyroxenoid that shows no solid solution with Di (Morimoto, 1989), occured in experiments 406 and 403. This mineral can occur in several associations, but it is commonly found in metamorphic associations (e.g., limestones), or carbonatites (Greenwood, 1967;Klaudius and Keller, 2006).…”

Section: Experiments Tºcmentioning

confidence: 99%

Study of silica-undersaturated magmas through the Kalsilite- Nepheline-Diopside-Silica system at 4.0 GPa and dry conditions

Souza

Conceição

Cedeño

et al. 2018

Geol. USP. Sér. cient.

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This study experimentally investigates the Kalsilite-Nepheline-Diopside-Silica system at high pressure and temperature, with emphasis on silica-undersaturated volume (leucite-nepheline-diopside -Lct-Nph-Di; and kalsilite-nepheline-diopside -Kls + Nph + Di -planes), at 4.0 GPa (~120 km deep), temperatures up to 1,400ºC and dry conditions, to better understand the influence of K 2 O, Na 2 O, and CaO in alkali-rich silica-undersaturated magma genesis. In the Lct-Nph-Di plane, we determined the stability fields for kalsilite (Kls ss ), nepheline (Nph ss ) and clinopyroxene (Cpx ss ) solid solutions, wollastonite (Wo) and sanidine (Sa); and three piercing points: (i) pseudo-eutectic Kls + Nph + Di + liquid (Lct 62 Nph 29 Di 9 ) at 1,000ºC; (ii) Kls + Sa + (Di + Wo) + liquid (Lct 75 Nph 22 Di 2 ) at 1,200ºC; and (iii) pseudo-eutectic Kls + Di + Wo + liquid (Lct 74 Nph 17 Di 9 ) at 1,000ºC. Kalsilite stability field represents a thermal barrier between ultrapotassic/potassic vs. sodic compositions. In the plane Kls-Nph-Di, we determined the stability fields for Kls ss , Nph ss and Cpx ss and two aluminous phases in smaller proportions: spinel (Spl) and corundum (Crn). This plane has a piercing point in Kls + Nph + Di(± Spl) + liquid (Kls 47 Nph 43 Di 10 ) at 1,100ºC. Our data showed that pressure extends K dissolution in Nph (up to 39 mol%) and Na in Kls (up to 27 mol%), and that these solid solutions, if present, determinate how much enriched in K and Na an alkaline magma will be in an alkaline-enriched metasomatic mantle. Additionally, we noted positive correlation between K 2 O and SiO 2 concentration in experimental melts, negative correlation between CaO and SiO 2 , and no evident correlation between Na 2 O and SiO 2 .Keywords: Experimental petrology; Alkaline rocks; Potassium; Mantle. ResumoEste trabalho trata do estudo experimental do sistema kalsilita-nefelina-diopsídio-sílica em condições mantélicas, com ên-fase em sua parte subsaturada em sílica (planos leucita-nefelina-diopsídio -Lct-Nph-Di; e kalsilita-nefelina-diopsídio -Kls + Nph + Di), a 4 GPa (profundidade de aproximadamente 120 km), até 1.400ºC em condições anidras. O objetivo é melhor compreender como K 2 O, Na 2 O e CaO influenciam a gênese de magmas ricos em álcalis e subsaturados em sílica. Para o plano Lct-Nph-Di, foram determinados campos de estabilidade para as soluções sólidas kalsilita (Kls ss ), nefelina (Nph ss ) e clinopiroxênios (Cpx ss ), além de wollastonita (Wo) e sanidina (Sa). Foram também definidos os pontos invariantes: (i) pseudoeutético Kls+Nph+Di+líquido (Lct 62 Ne 29 Di 9 ) a 1.000ºC; (ii) Kls + Sa + (Di + Wo) + líquido (Lct 75 Nph 22 Di 2 ) a 1.200ºC; (iii) pseudoeutético Kls + Di + Wo + líquido (Lct 74 Nph 17 Di 9 ) a 1.000ºC. O campo da kalsilita, nesse diagrama, representa um alto termal entre os extremos composicionais potássico/ultrapotássico vs. sódico. No plano Kls-Nph-Di, encontramos campos de estabilidade para Kls ss , Nph ss e Cpx ss , além de pequenas quantidades de espinélio (Spl) e coríndon (Crn) e um ponto...

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Nomenclature of pyroxenes.

Cited by 546 publications

References 5 publications

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications

Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

Study of silica-undersaturated magmas through the Kalsilite- Nepheline-Diopside-Silica system at 4.0 GPa and dry conditions

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Nomenclature of pyroxenes.

Cited by 546 publications

References 5 publications

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hoss&#233;r&#233; Dammougalr&#233; (Adamawa Plateau, Cameroon): Thermobarometric Implications

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hoss&#233;r&#233; Dammougalr&#233; (Adamawa Plateau, Cameroon): Thermobarometric Implications

Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

Study of silica-undersaturated magmas through the Kalsilite- Nepheline-Diopside-Silica system at 4.0 GPa and dry conditions

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Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications

Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hosséré Dammougalré (Adamawa Plateau, Cameroon): Thermobarometric Implications